DM: Physical Activity (2007)

Study Design:
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Quality Rating:
Research Purpose:
To evaluate the 6-month effects of exercise consultation on physical activity and the resultant effects on glycemic control and cardiovascular risk factors in people with type 2 diabetes.
Inclusion Criteria:
Participants had type 2 diabetes as defined by previously established criteria and controlled by diet, oral hypoglycemic agents or insulin and were in either a contemplation or preparation stage of exercise behavior change.
Exclusion Criteria:

Participants with concurrent medical conditions preventing exercise were excluded.

Description of Study Protocol:


Occurred during September 2000-2001.


  • Participants completed a maximum of five visits for study assessment. 
  • During the first visit, demographic details and current medications were recorded. BMI was calculated, and a peak exercise test was performed to screen participants for significant silent ischemic heart disease before randomization and to assess cardiopulmonary fitness. Participants were fitted with an accelerometer.
  • Visit two occurred about 7 days after visit one. Blood pressure was measured and a fasting blood sample taken for lipid profile, glycemic control, and fibrinogen. The stage and processes of exercise behavior change and 7-day physical activity recall were completed. All participants recieved standard exercise information and were randomly assigned to the experimental or control group.
  • Participants were randomly assigned on an individual basis in blocks of 20
  • Only experimental participants returned for visit three. At this time participants recieved an exercise consultation
  • At 6 months all outcome measures and procedures carried out at baseline were repeated.

Blinding used (if applicable):  Not possible

Intervention (if applicable)

  • Exercise consultation involved a 30 minute one-on-one discussion with a trained research assistant and was carried out following published guidelines.
  • The consultation was based on the transtheoretical model. Investigated were current physical activity, benefits, barriers, and costs of becoming more active, suitable activities, social support, goal setting and relapse prevention.

Statistical Analysis

  • Two-sample t tests were conducted to assess whether baseline measured variables were similar between the experimental and control groups. The effect of intervention was analyzed using paired t tests (between group). Non-parametric equivalent tests were used when the data did not follow a normal distribution. Categorical data are reported as a proportion and were analyzed using X2 or Fisher's exact test. P<0.05 was considered to be statistically significant. A Bonferroni correction was applied when a large number of comparisons were conducted to control for type 1 errors.
Data Collection Summary:

Timing of Measurements

Physiologic and biochemical indices were obtained at baseline and at 6 months.  At visit 3 an excercise consultation was given to the experimental group. Follow-up phone calls were given at 1 and 3 month intervals after the exercise consultation.

Dependent Variables

  • Physical activity levels - recorded from the accelerometer
  • Behavior change - from baseline to follow-up in stage of change categorized as progression, no change or regression
  • Cardiopulmonary exercise test - total exercise duration and peak gradient
  • BMI
  • Blood pressure
  • Glycemic control
  • Lipid profile
  • Fibrinogen

Independent Variables

  • Exercise consultation, a 30 minute one-on-one discussion based on transtheoretical modeling.

Control Variables

  • None noted
Description of Actual Data Sample:

Initial N:

Sampled population n=223, patients consented = 74, 70 patients were randomized, 35 to the experimental and 35 to the control group (35 males, 35 females)

Attrition (final N):

Experimental group = 32, control group = 31


Mean age of 57.6±7.9 years


Not noted by author

Other relevant demographics:

  • Mean BMI 34.6±6.8 kg/m2
  • Diabetes duration 6.0±4.5 years
  • 50 participants were obese (BMI>30 kg/m2)
  • 16 were overweight (BMI 25-30 kg/m2)
  • 4 were of normal weight (BMI<25 kg/m2)


No between-group differences were found at baseline

Location: Scotland

Summary of Results:

Changes in physiological and biochemical variables


Treatment Group

Mean change, baseline to follow-up

Control group

Mean change, baseline to follow-up

Between-group difference in change

P value

Exercise time (min)

 1.56 (0.24-3.20) -0.28 (-1.30-0.37)   56.6 to 231.5  <0.01

Peak gradient (%)



 0.94 to 4.1


Systolic blood pressure (mmHg)

 -3.67 (-15.53-8.20)

 7.14 (-4.51-18.80)

 -24.7 to -2.0

HbA1c (%)  -0.31 (-1.02-0.40)  0.37 (-0.35-1.10)  -1.23 to -0.07  <0.05
Fibrinogen (mg/dL)  -3.59 (-25.48 to 18.30)  21.53 (0.01 to 43.06)  -57.2 to -4.3  <0.05

Other Findings

More experimental participants increased stage of change (X2=22.6, P<0.001).

Author Conclusion:
Exercise consultation was more effective in promoting physical activity in people with type 2 diabetes than a standard exercise leaflet.  The participants receiving the exercise consultation increased their frequency of using four processes of change, and the majority reported an increase in stage of change. Positive changes were recorded in cardiovascular fitness, glycemic control and objective and subjective measures of physical activty. The control group recorded no signifcant changes.
Funding Source:
Reviewer Comments:
  • Sample size was limited and the time frame of 6 months may have been limited, however since all participants were homogeneous in terms of intentions to change physcial activity the sample size may be acceptable.
  • Recruitment was not specified except for date
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? ???
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? No
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? No
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? No
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes